Furnace for burning granular fuel



2 Sheets-'Sheet 1.,

(No Model.)

` ,0.3. P'ENFIELD. PURNAGE POR BURNING GRANULAR FUEL.

No. 469,749. Pmtente'dMar. 1, 1892..

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(No'ModeL) 2 Sheets-Sheet 2.

C. R. PE-NFIBLD. y PURNAGE FOR BURNING GRANULAR FUEL.

No. 469,749. y Patented Mar. l, 1892.l

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UNITED STATES PATENT 'rrrca.

FURNACE FOR BURNING GRANULAR FUEL.v

SPECIFICATION forming part Of Letters Patent N0. 469,749, (lated March1, 1892. Application liled May 28, 1891. Serial No. 394,489. (No model.)

T0 all whom it may concern:

Be it known that I, CHARLES R. PENFIELD, of Duluth, in the county of St.Louis and State of Minnesota, have invented a certain new and usefulImprovement in Furnaces for Burning Granular Fuel; and do hereby declarethat the following is a full, clear, and exact description of the same,reference being had to the drawings accompanying this specilication. d

My improvement relates to means for introducing a blast of air into thefurnace of a steam-boiler and equally distributing the same for burningsawdust, tan-bark, coaldust, and other granular' fuels in an effectivemanner. v

rlhe invention consists in the construction and arrangement of thelire-bed, as hereinafter more fully described and definitely claimed.

In the drawings, Figure l is a verticalcrosssection in line oo of Fig.2, showing three boilers set side by side and exhibiting my improvement.Fig. 2 is a longitudinal vertical section in line 'y y of Fig. l. Fig. 3is an enlarged sectional view across the air-trunk and lengthwise of oneof the distributing-tubes of the air-feeding apparatus. Fig. t is aperspective view of the same.

A A A indicate three steam-boilers set side' by side and inclosed insuitable brick-work. A greater or less number may be used. B is thefurnace or fire-place of the same.

My improvement is as follows: C is abridgewall located in thefurnace-space transversely of the boilers, the same rising to a suitableheight, but leaving sufficient space above the wall and under thelboilers for the passage of the draft to the rear of the boilers, asshown.

D is an air-trunk located in the nre-space, either at the front or backof the furnace, also extending transversely of the boilers and parallelwith the bridge-wall and connected at one end with a blower or otherdevice by which air is blownthrough the trunk. The trunk is of thesinuous or undulating form shown, being concave under each boiler andconvex between them, thereby forming hollows under the boilers, intowhich the fuel collects and by which a better combustion is maintained,and ridges between the boilers for dividing and spreading the fuel.

E E E are distributing air-pipes attached to the air-trunk and extendingcrosswise at right angles thereto, reaching nearly to or passing throughthe bridge-wall, as may be desired. Following the curves of theair-trunk, these air-pipes form hollow beds under the boiler, on whichthe fuel falls to be burned, and elevations between the boilers tospread the fuel. The top of the air-trunk and also the pipes have smallholes a a a, through which the air is forced in jets up through the bodyof fuel that falls on the pipes. The air, being forced in numerous jets,is equally distributed through the whole furnace-space. The airtrunk ispreferably made square and the lateral pipes round in cross-section. Themasonry is filled around the bottom and between the pipes, leaving onlythat part exposed in which the holes are located, and as cold air isbeing constantly forced through they do not easily burn out. The ends ofthe lateral pipes have small oppenings h b, through which jets of airareblown, the effect of which is to blowout any ashes or other materialthat may get into the pipes, thus keeping them clear.

G is a trough located above the boilers and transversely of the same andprovided with spouts c c c, which extend down at the sides of theboilers and open into the furnace-space above the air-pipes. Thesespouts may be provided with suitable cut-off valves to regulate the iowof the fuel through the same. At one end is a hopper d, into which thefuel is fed to be carried to the spouts. H is a conveyer consisting ofan endless band or apron resting in the trough and provided with lags,which catch the fuel and carry it. forward to the spouts. The apronpasses around suitable pulleys, to one of which motion is given tooperate the apron. By this means the fuel is fed evenly to the spoutsand dropped down between the boilers and upon the air-pipes below. Thefire-bed being undulating, the fuel forms in approximate shape, vaportion sliding down the sides of the ridges and filling the hollows toan even depth over all the pipes. Thus the fuel is spread ofsubstantially the same thickness throughout the bed, which would not bethe case if the bed were fiat, the fuel collecting in that case inpiles, leaving much of the fire-bed uncovered.

It is found in practice that green or wet IOO sawdust directly from thelog can-bereadily burned, requiring no special attention, except toregulate the supply.

Having described my invention, I do not claim thefuel-feeding'apparatus, as the same is old; but what I claim as new, anddesire to secure by Letters Patent, is- A l." The combination, with asteam -boiler furnace, of the air-trunk D, arranged in sinuous orundulating form, as described, adapted to receive grate-bars, as E, andprovided at its top with aseries of holes opening upward for the purposeof supplying jets of air to the fuel, as herein shown and described.

2. The combination, with a steamboiler `and described.

In witness whereof I have hereunto signed my name in the presence of twosubscribing witnesses.

CHARLES R. PENFIELD.

Witnesses:

AGNES M. STEBBINs, GEO. W. HAwKINs.

